Is the project finished and the builder paid in full?
If that's the case, then I don't think you have much hope of getting any help from him. Although you may be able to get him back with the understanding that the town would not be happy to know that he's doing this work without permits. That sort of "reminder" though could turn things into a very unfriendly situation.
If you plan to leave it be until you sell the house, then why tear it off before selling? The chance of it becoming an issue upon sale of the property is very slim, unless it's very obviously wrong, or an imminent hazard.